SINGAPORE/BEIJING (Reuters) - As China opens up its low-level airspace to civilian aircraft, the global aviation industry is laying the groundwork for a boom beyond private business jets and pilot training schools - with the purchase of fleets of air ambulance helicopters.

The freeing up of airways previously reserved for military use is a huge opportunity for Norbert Ducrot, head of Airbus Group's helicopters unit in China. Ducrot says there could be enough demand for more than 3,000 emergency medical choppers in China - up from as few as about 20 now in service.

While the United States already has more than 1,500 air ambulance helicopters, China's fleet is minimal because of the civilian airspace curbs. In a country where the World Health Organisation has estimated more than 250,000 annual road traffic deaths, air evacuations from both clogged Chinese city streets and remote rural areas could speed medical care and save lives.

The change proposed by China's State Council is set to ultimately raise the ceiling on airspace for general aviation to 3,000 meters from 1,000 meters. That would radically multiply both the heights and the routes air ambulances could use, a boon for pioneers like Qian Siwei's China Air Medical Service Ltd.

"Emergency air medical services have a great growth potential in China because our target customer is the general public, not just the privileged," Qian, a gynecologist by training, told Reuters. While the going rate for a helicopter evacuation is around 30,000 yuan ($4,565) per hour, companies like Qian's offer discount schemes that can cut costs by as much as 50 percent in some cases.

Based in the province of western Shaanxi, China Air Medical has a fleet of four helicopters and two business jets, operating with the backing of local authorities. Qian claimed his service has proved so popular that three other provinces have invited Chen Air Medical Service to set up similar operations.

China Air Medical is just one of a raft of operators across a broader aviation sector that Beijing is seeking to develop into a thriving home-grown industry. State-owned aircraft maker AVIC, which also supplies helicopters, is another.

But the liberalization is also enticing Western firms like Airbus and U.S. aircraft maker Textron Inc, keen to target what they see as a major growth opportunity.

HELIPADS 'COMPLICATED'

For Airbus executive Ducrot, the arithmetic is simple. He expects to sell 60 helicopters to China this year - for prices he declined to disclose - and for the country to buy up to 300 helicopters annually by 2025 as its economic growth still outpaces developed markets and liberalization kicks in.

"By 2025, China will become the most important helicopter market in the world," said Ducrot.

While some local authorities are enthusiastic, as in Qian's case, and some modern hospitals may be able to accommodate helipads, China's healthcare sector is already creaking and ageing hospital infrastructure may act as a brake on air ambulance growth.

At the Sichuan Provincial People's Hospital in the city of Chengdu, southwestern China, engineer Liu Xiaoxi, said that when the facility was under construction in the 1980s, a helipad was considered, but rejected as being "too complicated".

"It's difficult to add things on to the building, especially as tall towers have sprung up on all four sides," said Liu. While some hospitals would be able to add them, he said, "If you want to add a helipad on top of a building then you have to design that in early on in terms of the various beams and supports."

Still Beijing is ploughing ahead with reforms, despite uncertainty on issues like healthcare infrastructure, helipad construction and how Beijing will regulate a low-level civil aviation business.

GROWTH WARNING

China could have 2,000 general aviation airports by 2030 if the country opens the sector up to private investment, says Francis Chao, publisher of monthly publication China Civil Aviation Report and a contractor with the U.S. Federal Aviation Administration on U.S.-China aviation exchanges.

That compares with a projection by China's State Council of 500 airports by 2020.

But Chao warned growth could be restricted "without further relaxation on flight permits, availability of chartering and fuel supply, more and accessible airfield and flight services".

Apart from emergency medical services, companies like Airbus and Textron unit Bell Helicopters - which declined to comment for this story - are targeting sales in the rapidly growing domestic tourism market, fire-fighting and police services, and by companies that need to patrol pipelines and power lines.

For example, Airbus agreed to set up a final assembly line for its H135 helicopters in Hefei, Anhui province in October 2015. It's also investing in support services like sales offices, maintenance hubs and a training center for pilots - the latter being in short supply across the country. (http://reut.rs/1Uns7SG)

($1 = 6.5722 Chinese yuan renminbi)

(Reporting by Siva Govindasamy in SINGAPORE and Fang Yan in BEIJING; Additional reporting by SHANGHAI newsroom; Editing by Kenneth Maxwell)